Electric protective apparatus.



o. A. ROLPE. ELECTRIC PROTECTIVE APPARATUS.

APPLICATION FILED APE. 20, 1903.

Paentea 00u20, 1908.

fi Z/IJ Mig.

CHARLES A. ROLFE, OF ADItIAN, MICHIGAN, AS

ELECTRIC CO., OF ROCHESTER, NEW

SIGNOR, BY MEsNnAssIGNMENTs, To ROLFE YORK, A CORPORATION OF NEW YORK.

ELECTRIC PROTECTIVE APPARATUS.

Specification of Letters-Patent. v

Patented. Oct. 20, 1908.

Application filed April 20, 1903. .Serial No. 153,398.

A. ROLFE, a

` Prominent objects of my present invention are. to reduce the expenseof construction and maintenance of such devices; to secure simplicity ofconstruction and operation; and to accomplish `these results in aeffective manner.

' In the protective apparatus herein set forth I employ a material whichhas the property of a conductor, but has such a high internal resistanceas to generate heat upon the passage of a moderately strong currentthrough it, and which is also made readily fusible or softenable by amoderate increase in temperature. This material I include in the circuit,to be protected, and arrange in such shape or 30 form and/in connectionwith such devices, that during the passage of normal currents throughthe circuit the material will be unaffected and the circuit maintainedin desired normal condition; but when such current becomes undulystrong, the material.

will generate heat by its own resistance, and will become fused orsoftened by such heat and thereby cause or permit the circuit to becontrolled in any desired'way, as for example opened or grounded, orboth.

In the accompanying drawings,J I have shown three different forms ofprotective devices operating in this manner. In each of these formsIdesirably employ some spring means normally held in restraint by asuitable mass or quantity of such material, and arranged to operate tocontrol the circuit in any desired manner when the material is heatedand softened so as to release the spring means. 'It will be ap rent thatthe material can be used in an in ite variety of ways and formsofprotective devices, Yand practical and hence it will be understood thatthose herein shown are merely illustrative of the manner of employingthe same.

In the accompanying drawings, Figure 1 is a view of one form ofprotective device embodying my present invention; Fig. 2 is a view ofdetails of construction of such de-l vice; Figs. 3 and 4 are views ofanother form of device, Fig. 3 showing the device in its normal orunoperated condition, andl Fig. 4. showing the same after operation;Figs. 5 and 6 are similar views of'another form of device; and Figs. 7and 8 are views of details of construction of the device of Figs'..3 and4.

Referring first to the device shown. in Figs. 1 and 2, such deviceconsists of a base 1 made of insulating material such as porcelain,slate or the like, and provided with terlninals 2 and 3 to which thecircuit wires are understood to be properly connected. A spring 4 issecured to the base 1 at the inner end of the terminal 3, and extendstoward the terminal 2. The latter is provided with an upwardly extendingarm 5 having a socket 6, and in this socket is fitted a shell 7containing a quantity or mass 8 of material ofithe kind hereinbeforementioned, namely,

a conducting material having a sufficientlyv high internal resistance togenerate heat, and capable of softening or fusing upon moderateincreaseof temperature. This material.

can be of any suitable or desired composition, capable of giving theresults mentloned. I find a very desirable composition, however,

to be a non-conducting softenable material,` Y`

such as wax, resin'or the like, combined with a powdered conductor suchas powdered carbon, graphite, copper or the like. The relativeproportions of the two parts,-that.is of the non-conducting wax andpowdered conductor,-can bel varied so as to secure materials havingdii'erent degrees of conductivity, or different specific resistances asmay be required or desired to meet different conditions. The proportionsmay be so varied as to'secure widely differing results. This compositioncan be conveniently made by melting a suitable quantity of thenon-conducting material such as wax or similar substance, and thenadding the powdered conducting material thereto in desired quantityWhile the wax is still hot, and then permit-- p that the mixture ishomogeneous throughout.

A hook or rod 9 is embedded in the mass of material 8 and engages thefree end of the spring 4. The circuit, vit will be seen, is made fromthe circuit wires 10 and 11 through the spring 4, hook 9, mass ofmaterial 8, shell 7 and arm 5. Under normal conditio'ns the device isinthe condition shown in Fig. 1. WhenA an unduly,4 strong currenttraverses the circuit, however, it

-heats the mass of material 8 by.' reason of the. internal resistance ofthe same and the heat thus generated causes this material toflbecomefused or softened, thereby allowing the spring 4 to withdraw the hook 9,whereupon the spring 4 retracts and opens the circuit. 4

In the'arrangement shown in Figs. 3 and 4, a base 12 is provided with apair of spring posts 13 and 14, and these support a cylindric cartridge15 having its-ends provided with caps 16, 16 adapted `to engagethe upperends of the posts 13 and 14. The main bodyof the cartridge 15 ismaterial of the kind specified, and it serves to hold the posts 14underrestraint, as shown in Fig.

3. Local circuit contacts 17 and 18 are arrangedon the base 1 at `oneside of the spring 14, and on the ot l erside of the spring 13 isarranged a lightning arrester carbon 19. Thisl latter is interposedbetween a ground contact 20 anda line contact 21. The

spring post 13 is provided with a plug or arm 22 adapted to strikeagainst the contact 20 when tlie spring 13 is released.. The wires 23,23, of the circuit under protection, are connected with the posts 13 and14 at.the

bases thereof. A ground-wire is connected,

with the ground contact 20 and local circuit wires are connected withthe contacts 17 and 18. Under normal conditions the device is in theposition shown in Fig. 3. On the.passage of an unduly strong current,however, the high resistance softenable conducting material in thecartridge 15, heats and then softens, thereby releasing the springs 13and 14,' the former of which .springs out and strikes against thegroundcontact 20, thereby grounding one side of the circuit, and theother o f which springs out and strikes against the contact 17, 4therebyvforcin the same against the contact 18 and closlng a local circuitwhich is arranged to operate in any desired or preferred manner.

The arrangement shown in Figs. 5 and 6 is similar to the arrangementshown in. Figs. 3 and 4, except that the. spring posts 13 and 14* areadapted to) spring* toward one another instead of awayfrom one anotheras in the former arrangement. This tendency on the part of the springsto ycome'together is opposed by a plug 15a of high resistance softenableconducting material, which when heated and softened by an unduly lstrongcurrent, becomes compressed as shownV in Fig.l 6. The post 14a isprovided with a long arm or rod 225 adapted to come .in contact with theground Contact 20, andthe post ,13a is provided with a screw- 24 forming a stop to limit the approachin 'move ment of the springs 13a and14a. 'Ilhe local circuit contacts 17EL and 18a are made, the former witha straight end and the latter with a long bent end 25. The device in auunoperated condition is shown in Figs, and in operated condition in Fig.6, in which latter figure it will be seen that the long arm or rod 22ahas come into contact with the ground contact 20 and the spring 14s hascome against the stop 24, while the local circuit contact 1S"L hassprung over against the other local circuit contact 17a. arrangement itwill be seen thecircuit is grounded by the arm 22il coming against theground contact 20, and is also short-circuited by the spring 14 meetingthe stop 24.

It will be seen that the devices thus oonstructed 'are exceedinglysimple, the Duur ber of parts being reduced to a minimum. Instead ofemploying two separate devices, one a softenable material and the othera In this' i n heat concentrating device for actingy upon the same, inaccordance with the manner of construction of protectors now andheretofore in common use, I secure vthese results by a single materialwhich has the combined properties of concentrating heat and of softuening upon the development of a moderate extent of heat, nd thus Idispense with one of the instrumentalities now commonly ein ployed inprotectors, and also simplify the' largely reduced, because thenecessity ofwinding heat coils, of making connections, f

etc. etc. can be avoided and .instead the material made in largequantity and formed or molded into desired shape in the simplestpossible methods..

Inthethree arrangements above set-itorth, it will be seen that I haveshown simple and practical devices for opening the circuit, for openingand grounding the same, and for short-rircuiting and grounding the same,respectively. It will be readily seen that many other-'and varieddevices can be devised for accomplishin other results It will be wellunderstood, therefore, that I do not` intend to limit my self to theparticular form of devices herein 0f these results and`j i u ce setforth, nor to the construction which they possess.

That l claim as my invention is ln u device of the class specified, anonconductin` softenable material, comprising wax, rosin, and apowderedconductor.. in combination with circuit controlling spring actuateddevices, held normally -in position luy said softenable material, andreleased CHARLES A. ROLFE. Witnesses A. MILLER BELFIEIJD,

I. C. LEE.

